KINESIOLOGY NOTES
An introduction to movement
MOVEMENT
Why important: Basic feature of all animal life. Helps body adapt to
environment demands.
How body moves: System of levers in body gives wide variety of movements +
resilience to rigid bones.
THE BODY LEVERS
Parts:
1. Bones = rigid bars/arms of lever
2. Joint = fulcrum where movement happens
Joint structure: Shape + function linked. Articular surface shape decides
movement type. Normal movement = rarely only 1 direction.
Rule: No lever works without force applied.
FORCES APPLIED TO BODY LEVERS
Types:
1. External force = from outside body. Ex: gravity, physio’s hand pressure.
2.Internal force= from inside body = muscle contraction.
Direction of movement: Decided by force direction. Gravity = toward earth
center. Muscle pull = muscle’s pull direction.
,Muscle force: Applied at muscle’s bone attachment. Pull direction = muscle
position.
Reality: Body levers rarely get 1 force. Usually 2+ forces combine/oppose. If
forces equal = balance, no movement.
TYPES OF MOVEMENT AND POSTURE
Passive Movement: Muscles inactive/relaxed. Movement by external force
only.
TYPES OF MOVEMENT
Passive Movement: External force moves limb, muscles inactive.
Active Movement: Movement from muscle contraction.
Posture: Body held by internal/external forces. Can be *Inactive Posture* =
rest OR *Active Posture* = muscles working for stability.
TYPES OF MUSCLE CONTRACTION
1. Isometric: "Iso" = equal, "metric" = length. Force ↑ but muscle length NO
change. Ex: pushing wall.
2. Isotonic: Force ↑ + muscle length changes. Can shorten or lengthen.
TYPES OF MUSCLE WORK
Work = force × distance. 3 types to control/move body levers:
1. Static Muscle Work: Isometric contraction. Muscle holds/balances but no
movement = no work done. Called "static" to separate from
concentric/eccentric.
2. Concentric Muscle Work: Isotonic shortening. Muscle ends move
"concentric-towards centre". Movement = direction of muscle pull. Ex: biceps
curl up.
,3. Eccentric Muscle Work: Isotonic lengthening. Muscle ends move
"eccentric-from centre" to oppose bigger force. Movement = opposite to
muscle pull. Ex: biceps curl down slowly.
RANGE OF MUSCLE WORK
Excursion: Amount muscle can shorten/lengthen. Max ≈ 50% of max extended
length.
Full range: Max possible excursion. Inner range: Movement near shortest
muscle position. Outer range: Movement near longest muscle position.
Middle range: Between inner + outer.
1-line trick: Contraction: Isometric = length same, Isotonic = length change.
Work: Static = hold no move, Concentric = shorten/pull, Eccentric =
lengthen/brake. Range: Inner = short, Outer = long, Full = 50% max.
RANGE OF MUSCLE WORK –
Middle range: Muscle neither fully shortened nor fully extended during work.
THE STRENGTH OF MUSCLE CONTRACTION
Meaning: Muscle’s ability to make tension = intra-muscular tension.
Rule: Strength ∝ tension needed to beat opposing forces.
Control: Variation in strength by "motor units system".
A MOTOR UNIT: 1 motor neuron + group of muscle fibers it supplies.
Rule: When neuron = Anterior Horn Cell fires, ALL fibers in that unit contract
together = "all-or-none".
Strength of whole muscle: Depends on number of motor units activated.
Weak contraction = few motor units. Maximal contraction = all motor units
firing.
THE GROUP ACTION OF MUSCLES
, Rule: 1 muscle never works alone for movement/stability. Muscles work in
groups.
Purpose of groups: Efficient functional movement + exact direction + control
in part of range.
4 Groups:
1. Agonists / Prime Movers: Contract to make force for movement.
2. Antagonists: Oppose agonist. Relax/inhibit gradually to control + allow
smooth movement.
3. Synergists: "Syn = with". Work _with_ agonists. Help + modify pull
direction of agonist.
4. Fixators: Not fully shown here = stabilize joint/base.
GROUP ACTION OF MUSCLES -
4. Fixators: Stabilize bones of origin of agonists. 2 jobs: 1. Make agonist more
efficient 2. Keep body stable as a whole. Ex: muscles crossing 2+ joints.
PATTERNS OF MOVEMENT
Pattern: Site + direction of a movement. Many patterns possible.
Mass movement: Most functional movements use several joints together.
Single joint movement: Learned/"distilled" from mass patterns by conscious
practice. Ex: everyday activities = mass movement.
TIMING IN MOVEMENT
Timing: Sequence + force of muscle contractions.
Good timing: Each force peaks max when next force adds on it = no effort
wasted. Fig 26 "Good timing"
Bad timing:
1. Too slow: Peak missed, force wasted. Fig 26 "Timing too slow"
An introduction to movement
MOVEMENT
Why important: Basic feature of all animal life. Helps body adapt to
environment demands.
How body moves: System of levers in body gives wide variety of movements +
resilience to rigid bones.
THE BODY LEVERS
Parts:
1. Bones = rigid bars/arms of lever
2. Joint = fulcrum where movement happens
Joint structure: Shape + function linked. Articular surface shape decides
movement type. Normal movement = rarely only 1 direction.
Rule: No lever works without force applied.
FORCES APPLIED TO BODY LEVERS
Types:
1. External force = from outside body. Ex: gravity, physio’s hand pressure.
2.Internal force= from inside body = muscle contraction.
Direction of movement: Decided by force direction. Gravity = toward earth
center. Muscle pull = muscle’s pull direction.
,Muscle force: Applied at muscle’s bone attachment. Pull direction = muscle
position.
Reality: Body levers rarely get 1 force. Usually 2+ forces combine/oppose. If
forces equal = balance, no movement.
TYPES OF MOVEMENT AND POSTURE
Passive Movement: Muscles inactive/relaxed. Movement by external force
only.
TYPES OF MOVEMENT
Passive Movement: External force moves limb, muscles inactive.
Active Movement: Movement from muscle contraction.
Posture: Body held by internal/external forces. Can be *Inactive Posture* =
rest OR *Active Posture* = muscles working for stability.
TYPES OF MUSCLE CONTRACTION
1. Isometric: "Iso" = equal, "metric" = length. Force ↑ but muscle length NO
change. Ex: pushing wall.
2. Isotonic: Force ↑ + muscle length changes. Can shorten or lengthen.
TYPES OF MUSCLE WORK
Work = force × distance. 3 types to control/move body levers:
1. Static Muscle Work: Isometric contraction. Muscle holds/balances but no
movement = no work done. Called "static" to separate from
concentric/eccentric.
2. Concentric Muscle Work: Isotonic shortening. Muscle ends move
"concentric-towards centre". Movement = direction of muscle pull. Ex: biceps
curl up.
,3. Eccentric Muscle Work: Isotonic lengthening. Muscle ends move
"eccentric-from centre" to oppose bigger force. Movement = opposite to
muscle pull. Ex: biceps curl down slowly.
RANGE OF MUSCLE WORK
Excursion: Amount muscle can shorten/lengthen. Max ≈ 50% of max extended
length.
Full range: Max possible excursion. Inner range: Movement near shortest
muscle position. Outer range: Movement near longest muscle position.
Middle range: Between inner + outer.
1-line trick: Contraction: Isometric = length same, Isotonic = length change.
Work: Static = hold no move, Concentric = shorten/pull, Eccentric =
lengthen/brake. Range: Inner = short, Outer = long, Full = 50% max.
RANGE OF MUSCLE WORK –
Middle range: Muscle neither fully shortened nor fully extended during work.
THE STRENGTH OF MUSCLE CONTRACTION
Meaning: Muscle’s ability to make tension = intra-muscular tension.
Rule: Strength ∝ tension needed to beat opposing forces.
Control: Variation in strength by "motor units system".
A MOTOR UNIT: 1 motor neuron + group of muscle fibers it supplies.
Rule: When neuron = Anterior Horn Cell fires, ALL fibers in that unit contract
together = "all-or-none".
Strength of whole muscle: Depends on number of motor units activated.
Weak contraction = few motor units. Maximal contraction = all motor units
firing.
THE GROUP ACTION OF MUSCLES
, Rule: 1 muscle never works alone for movement/stability. Muscles work in
groups.
Purpose of groups: Efficient functional movement + exact direction + control
in part of range.
4 Groups:
1. Agonists / Prime Movers: Contract to make force for movement.
2. Antagonists: Oppose agonist. Relax/inhibit gradually to control + allow
smooth movement.
3. Synergists: "Syn = with". Work _with_ agonists. Help + modify pull
direction of agonist.
4. Fixators: Not fully shown here = stabilize joint/base.
GROUP ACTION OF MUSCLES -
4. Fixators: Stabilize bones of origin of agonists. 2 jobs: 1. Make agonist more
efficient 2. Keep body stable as a whole. Ex: muscles crossing 2+ joints.
PATTERNS OF MOVEMENT
Pattern: Site + direction of a movement. Many patterns possible.
Mass movement: Most functional movements use several joints together.
Single joint movement: Learned/"distilled" from mass patterns by conscious
practice. Ex: everyday activities = mass movement.
TIMING IN MOVEMENT
Timing: Sequence + force of muscle contractions.
Good timing: Each force peaks max when next force adds on it = no effort
wasted. Fig 26 "Good timing"
Bad timing:
1. Too slow: Peak missed, force wasted. Fig 26 "Timing too slow"
